Crushers of this sort are known, for example, from U.S. Pat. No. 5,248,101 issued to Rose et al. These crushers are employed for crushing all sorts of materials, especially rocks and recently also in cement making. The material to be crushed is poured through the feed device onto the turntable and is thrown, under the action of the ejectors and under the effect of centrifugal force, violently towards anvils on which it shatters to fall, in crushed form, to the bottom of the crusher from where it is discharged.
It is obvious that the ejectors and, above all, the anvils undergo very violent stressing and are subject to rapid wear. The anvils in particular must absorb the significant impacts caused by the material thrown by the ejectors. It even happens that anvils break up under the impact of abnormally massive pieces or when, which may also happen, an ejector is detached and thrown against the anvils.
For the anvils to resist as well as possible, they need to be fixed at such a height that they receive most of the projectiles at their centre. This appropriate fastening in terms of height causes no problems if the crusher is always used to crush the same materials with constant particle size. In contrast, if the particle size of the material to be crushed changes, the trajectory of the material thrown by the ejectors varies so that the anvils, which are mounted at a fixed height, receive the projectiles on the upper or lower edges and therefore wear much more quickly. It may even happen that the material does not reach its target and becomes crushed below the anvils, on the lining of the housing.
In order to overcome this risk and be able to use a crusher for various particle sizes, systems have already been proposed for vertical adjustment of the height at which the anvil ring is fixed.
One of these systems consists in mounting the anvil ring on sorts of helicoid ramps fixed to the internal wall of the housing and having several ledges at various levels for supporting the anvil ring. In order to change the height at which the anvils are positioned, it is therefore sufficient to lift up the ring, turn it through a given angle and place it on a higher or lower ledge. This system suffers from the handicap that the wall of the housing must be pierced for fixing the ramps for supporting the ring or that there is a need to provide welds for fixing the ramps to the wall.